JPH0830034B2 - Optically active compound and its use - Google Patents

Description

The present invention relates to a novel optically active compound, a liquid crystal composition containing the compound, and a liquid crystal composition containing the compound or at least one of the compounds as a component. The present invention relates to an optical switching element which is configured by using the optical switching element.

[Conventional technology]

Liquid crystal display elements currently widely used in practice are the twisted nematic type (TN) and the dynamic scattering type (DS). Although these are displays by a nematic liquid crystal cell whose main component is nematic liquid crystal, one of the disadvantages of the conventional nematic liquid crystal cell is that the response speed is slow, and the fact that only a response speed of the order of several milliseconds at the maximum can be obtained. can give. This is one of the factors that limit the application range of nematic liquid crystal cells. On the other hand, it has recently become clear that a faster response can be obtained by using a smectic liquid crystal cell.

It is known that some optically active smectic liquid crystals exhibit ferroelectricity, and there is great interest in their applications. Ferroelectric liquid crystal, RB, 1975
It was first synthesized by RB Meyer et al. [J. Phys. ) -2'-Methylbutylcinnamate (DOBAMBC) is a typical Schiff base compound which exhibits ferroelectricity in an optically active state, for example, a chiral smectic C phase. It is. Later, NA Clark et al. [Applied Physics Letts.
Vol. 36, p. 899 (1980)] found that a microsecond-order high-speed response was found in a thin film cell of DOBAMBC, which triggered the ferroelectric liquid crystal to utilize its high-speed response and memory property. In addition, it is attracting attention as a material that can be used not only for displays such as liquid crystal televisions, but also for parts of optoelectronic-related elements such as optical printer heads, optical Fourier transform elements, and light valves. In a ferroelectric liquid crystal cell, the use of a material having a high dielectric constant and a large spontaneous polarization is advantageous because the cell can be driven at a high speed, and therefore a material having a large spontaneous polarization is desired.

In practical use, it is necessary that the liquid crystal compound or the composition itself be stable, and that it exhibit ferroelectricity in a wide temperature range centered at room temperature.

[Problems to be Solved by the Invention]

However, a Schiff base type compound such as DOBAMBC has a problem in stability against water and light, and has a ferroelectric temperature range of 40 ° C. or more higher than room temperature. There wasn't. Therefore, realization of a material system which is physically and chemically stable and has a large spontaneous polarization is strongly expected as a ferroelectric liquid crystal material.

An object of the present invention is to obtain a novel optically active compound which is excellent in chemical stability and photostability, has a large spontaneous polarization, and has a wide temperature range of the chiral smectic C phase. Another object of the present invention is to provide a display element or the like having a high-speed response using such an optically active compound or a liquid crystal composition.

[Means for solving the problem]

In summary, the first invention of the present invention relates to an optically active compound and has the following general formula I: [In the formula, W, X, Y and Z are fluorine or chlorine, m is a number of 1 or 2, R is an alkyl group having 4 or more carbon atoms, an alkyloxy group or an alkyloxycarbonyl group, and C ₃ F ₇ OC
At least one of the F (CF ₃ ) group and the group R is an optically active group].

The second invention of the present invention is an invention relating to a liquid crystal composition, comprising at least one of the optically active compounds of the first invention.
It is characterized by containing a seed as a component.

A third invention of the present invention relates to an optical switching element, which is constituted by using the optically active compound of the first invention or a liquid crystal composition containing at least one of the compounds as a component. It is characterized by

The compound of the general formula (I) has a central skeleton having a benzoic acid ester structure, and further has long-chain substituents (preferably having 4 to 18 carbon atoms) at both ends of the molecule. It exhibits liquid crystallinity. In addition, this compound has a high optical rotatory power because a carbonyl group is directly bonded to the asymmetric carbon and the dipole moment of fluorine or chlorine acts laterally with respect to the long axis of the molecule. In addition, it is expected that the resistance to domain rotation will be reduced in a thin cell, which is indispensable for ferroelectric liquid crystals, compared to non-fluorine-based compounds because the surface energy is reduced by the presence of multiple fluorines. However, high speed response can be expected when these are used as a display element in a panic.

[Compound production method]

The optically active compound of formula (I) in the present invention can be produced, for example, according to the following synthetic route.

When the above production process is outlined, an optically active perfluoro-
2-Propyloxypropionyl chloride (II) and 4
-Reacting with hydroxypolyfluorobenzoic acid (III) in the presence of a basic substance to produce a carboxylic acid compound (IV). (IV) is converted to an acid chloride (V) with a chlorinating agent such as thionyl chloride.

The compound (III) was prepared according to Reference 1: Birthal (JMBirha
ll) et al., Journal of Chemical Society (J. Chem. Soc.), 1971, p. 1343, or Reference 2: Akio Takaoka, Nobuo Ishikawa, et al., The Chemical Society of Japan, 1985, p. It can be prepared from fluoro- or pentachloro-benzonitrile.

The details are as described in Japanese Patent Application No. 63-110484.

Finally, the acid chloride (V) can be reacted with the phenol compound (VI) in the presence of a basic substance to produce the compound represented by the general formula I.

When racemic perfluoro-2-propyloxypropionic acid is used, a compound of the general formula (I) in which the alkyl group in the group R of the compound of the general formula (VI) is optically active is used. Can be manufactured.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 (A) Optically active-perfluoro-2-propyloxypropionic acid chloride 3.5 g as a toluene solvent,
Hydroxytetrafluorobenzoic acid (III) hydrate 2.3
Gradually add dropwise to a solution of 30 g of pyridine at 55-65 ° C for 5 hours, let stand overnight, add water to extract with ether, wash with water and dry over anhydrous magnesium sulfate. It is then purified by column chromatography on silica gel using hexane as a solvent, and 4- (perfluoro-
1-Propyloxyethyl) carbonyloxytetrafluorobenzoic acid (IV) was obtained.

(B) To 1.3 g of the compound (IV) obtained in (a), 10 ml of thionyl chloride was added, and after heating for 2 hours, thionyl chloride was distilled off under reduced pressure to obtain a toluene solution, and 4-decyloxyphenol (VI ) Gradually drop it in a solution of 0.7 g of pyridine in 30 ml and react at 57-66 ° C for 5 hours, and leave it overnight, then 1%
It was washed with an aqueous solution of sodium hydroxide and then with water, dried over anhydrous magnesium sulfate, the solvent was distilled off, and the residue was purified by column chromatography on silica gel using hexane-toluene as a solvent and further at low temperature using heptane. Recrystallized and compound: 4- (perfluoro-1-propyloxyethyl) carbonyloxytetrafluorobenzoic acid-
The 4'-decyloxyphenyl ester was prepared.

(C) Encapsulating this compound in a glass cell with a transparent electrode gap of about 3 μm, and observing it with a polarization microscope while applying an electric field of ± 5 V and 1 Hz, the domain also reverses from 12.4 ° C when the temperature drops. It was approved to do. Other phase transition temperatures are shown in Table 1 below together with other examples. Note that
Cry is a crystalline state and SC * is a ferroelectric chiral smectic C phase, which is a phase in which at least a part responds to the above electric field. SA indicates the smectic A phase, Ch indicates the cholesteric phase, and I indicates the isotropic liquid phase. Also, -indicates that the phase exists. Note that () indicates that the phase is monotropic, and- indicates that the existence of the phase is not clear.

This compound was enclosed in a cell with an electrode gap of 120 μm, and the triangular wave method [K. Miyasato, S. Abe, H. Takezoe, A. Fukuda and E. Kuse (K. Miyasato, S. Abe, H. Takez
oe, A.Fukuda, E.Kuze), Japanese
Of Applied Physics (Jpn.J.Appl.Phys.),
In 1983, Vol. 22, L661, the spontaneous polarization was measured and found to be 128 nC / cm ² .

Example 2 4-Hydroxytetrafluorobenzoic acid in place of 4-
The compound: 4- (perfluoro-1-propyloxyethyl) carbonyloxy-3 was prepared in the same manner as in Example 1 except that hydroxy-3-chlorotrifluorobenzoic acid was used.
-Chlorotrifluorobenzoic acid-4'-decyloxyphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

The spontaneous polarization value measured in the same manner as in Example 1 is 16
It was 8 nC / cm ² .

Example 3 4-Hydroxytetrafluorobenzoic acid in place of 4-
Hydroxy-2-chlorotrifluorobenzoic acid, Compound 4- (perfluoro-1-propyloxyethyl) carbonyloxy-in the same manner as in Example 1 except that 4-decyloxyphenol was used in place of 4-decyloxyphenol. 2-Chlorotrifluorobenzoic acid-4'-decylphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

The value of spontaneous polarization measured in the same manner as in Example 1 is 10
It was 5 nC / cm ² .

Example 4 4-octyloxy-4'-hydroxybiphenyl was used in place of 4-decyloxyphenol, and compound: 4 was used in the same manner as in Example 1 except that chloroform-hexane was used as the solvent for the column chromatography in (b).
-(Perfluoro-1-propyloxyethyl) carbonyloxytetrafluorobenzoic acid-4 "-octyloxy-4'-biphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

The spontaneous polarization value measured in the same manner as in Example 1 is 87.
It was nC / cm ² .

Example 5 Compound: 4- (perfluoro-1-propyloxyethyl) carbonyloxytetrafluoro in the same manner as in Example 1 except that 4'-hydroxy-4-biphenylcarboxylic acid decyl ester was used in place of 4-decyloxyphenol. Benzoic acid-4 "-decyloxycarbonyl-
The 4'-biphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

Example 6 4-Hydroxytetrafluorobenzoic acid in place of 4-
Hydroxy-3-chlorotrifluorobenzoic acid, 4'-hydroxy-4-in place of 4-decyloxyphenol
Using biphenyl carboxylic acid hexyl ester, (b)
The compound was prepared in the same manner as in Example 1 except that chloroform-hexane was used as the solvent for the column chromatography in Example 1.
: 4- (Perfluoro-1-propyloxyethyl) carbonyloxy-3-chlorotrifluorobenzoic acid-
4 ″ -hexyloxycarbonyl-4′-biphenyl ester was prepared. The phase transition temperature of this compound is shown in Table 1.

The spontaneous polarization value measured in the same manner as in Example 1 is 14
It was 5 nC / cm ² .

Example 7 4-Hydroxytetrafluorobenzoic acid in place of 4-
Hydroxy-3,5-dichlorodifluorobenzoic acid, 4-
4-octyloxy-instead of decyloxyphenol
Compound: 4- (perfluoro-1-propyloxyethyl) carbonyloxy-3,5-dichlorodifluorobenzoic acid-4 ″ -octyloxy-4 was prepared in the same manner as in Example 1 except that 4′-hydroxybiphenyl was used. The'-biphenyl ester was prepared.

The phase transition temperature of this compound is shown in Table 1.
Although the * phase was not shown, the expression of the SC * phase was observed by mixing with the non-chiral liquid crystal compound as shown in Example 9.

Example 8 Optically active-racemic compound in place of perfluoro-2-propyloxypropionic acid, 4-hydroxy-2-chlorotrifluorobenzoic acid in place of 4-hydroxytetrafluorobenzoic acid, optical in place of 4-decyloxyphenol Active-4- (1-methylheptyloxy)-
The compound: 4- (perfluoro-1-propyloxyethyl) carbonyloxy-2-chlorotrifluorobenzoic acid-4 ″-(1-methylheptyl) was prepared in the same manner as in Example 1 except that 4′-hydroxybiphenyl was used. Oxy)-
The 4'-biphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

The spontaneous polarization value measured in the same manner as in Example 1 was 55 nC / c.
It was m ² .

Example 9 << Liquid Crystal Composition >> 4 ′ of the following structural formula, which is a non-chiral smectic liquid crystal, relative to 20 parts by weight of the compound produced in Example 7.
25 parts by weight of-(2-methylbutyl) -4-biphenylcarboxylic acid (4-octyloxyphenyl) ester and 55 parts by weight of 4'-octyloxy-4-biphenylcarboxylic acid (4-nonyloxyphenyl) ester A part was mixed to prepare a liquid crystal composition.

This liquid crystal composition showed the SC * phase in the range of 10 to 62 ° C., and its temperature range was remarkably expanded as compared with the single compound.

Example 10 << Liquid Crystal Composition >> The non-chiral smectic liquid crystal in Example 9 was respectively added to 10, 12 and 15 parts by weight of the compounds produced in Examples 1, 2 and 5, respectively.
A liquid crystal composition was prepared by mixing 40 and 23 parts by weight. This liquid crystal composition showed an SC * phase in the range of 6 to 59 ° C., and its temperature range was remarkably expanded as compared with the single compound.

As shown in the above two examples, by mixing the liquid crystal compounds having different structures, the chiral smectic C can be obtained in a wider temperature range than in the case of using them alone, and above and below room temperature.
A liquid crystal composition serving as a liquid crystal can be obtained.

Example 11 << Optical switching element >> A glass cell having a polyimide film subjected to a rubbing orientation treatment and having a transparent electrode gap of about 3 μm was filled with the compound obtained in Example 3 as an isotropic liquid by heating. This cell was gradually cooled and kept at 24 ° C, and the change in transmitted light intensity when a ± 20 V, 10 Hz square wave was applied was measured with a photomultiplier tube, and the response time due to 0 to 90% change in light intensity was observed. Is 210 μs
It was ec and showed high-speed response.

Example 12 << Optical switching element >> A cell was prepared in the same manner as in Example 11 using the liquid crystal compositions prepared in Examples 9 and 10. The response times obtained under the same conditions as in Example 11 except that the measurement temperature was 35 ° C.
It was 140 and 50 μsec, showing high-speed response.

〔The invention's effect〕

As described above, according to the present invention, the spontaneous polarization is large by using the optically active compound represented by the general formula I or the liquid crystal composition containing at least one of the optically active compounds as a component. When used as a display element, it is possible to provide not only a high-speed response but also a material system and an optical switching element exhibiting a chiral smectic phase in a wide temperature range.

Claims (3)

[Claims] (1) The following general formula (I): [In the formula, W, X, Y and Z are fluorine or chlorine, m is a number of 1 or 2, R is an alkyl group having 4 or more carbon atoms, an alkyloxy group or an alkyloxycarbonyl group, and C ₃ F ₇ OC
At least one of the F (CF ₃ ) group and the group R is an optically active group]. 2. A liquid crystal composition comprising at least one optically active compound according to claim 1 as a component. 3. An optical switching element comprising the optically active compound according to claim 1 or a liquid crystal composition containing at least one of the compounds as a component.